KR20130089633A - Multiple-stage indicating desiccant - Google Patents

Abstract

The present invention provides a multistage indicating desiccant comprising a) at least one aluminosilicate co-gel, b) at least one iron source, and c) at least one bromide source, wherein at least partially the alumine is at least partially alumina. A multistage indicating desiccant and a method and use of the multistage indicating desiccant are supported on nosilica co-gel.

Description

Multi-Level Instruction Desiccant {MULTIPLE-STAGE INDICATING DESICCANT}

The present invention relates to indicator desiccants and methods of making the indicator desiccants and their use in the various desiccant applications, in particular in the various desiccant applications requiring monitoring of humidity.

Silica-based desiccants are used in various fields requiring a dry environment. A prominent problem in this area is to further ensure a minimum level of drying, in which the capacity of the desiccant is maintained to maintain an environment below a certain level of relative humidity (RH) over a given time, and the saturation level of the desiccant with moisture is specified. It concerns questions about when replacement of desiccants and / or regeneration is required. In this respect, a great deal of effort has been made to provide the desiccant with an indication means, in particular with regard to the visual assessment of the level of moisture present in a given desiccant.

To this end, various indicators have been developed based on the use of inorganic or organic compounds in silica-based materials, where the compounds change color as a function of the saturation level of the desiccant by moisture. Using this principle, a number of indicator desiccants have been successfully developed and the materials obtained cover a wide range of saturation to the relative humidity present in the environment. In particular, it has developed a set of materials to meet specific needs in countless applications. More specifically, depending on the highest level of relative humidity that can be tolerated for a particular application, the indicator desiccant may be selected such that the color change matches the saturation level of the desiccant with moisture, where the desiccant still retains the required drying activity. It can be provided, but it is required to be quickly replaced with a new desiccant to ensure the required level of drying for a long time.

In the case of indicator desiccants developed in the past, on the one hand, in terms of the stability of the indicator, in particular in terms of the stability of the organic indicator compound, Problems have been raised in terms of toxicity of the indicator compounds.

In view of these problems, indicator desiccants containing inorganic indicator compounds with low toxicity have been developed. For example, WO # 00/65339 A1 discloses humidity indicator compounds comprising iron salts as activity indicators. However, these indicator desiccants have disadvantages in terms of color change, and the color change is not pronounced, but rather the color change develops gradually as the saturation of the desiccant by moisture increases.

For this purpose, it has been found that bromide as an anion component can make the color change more pronounced, in particular a sharp color change at a certain level of relative humidity. Accordingly, WO # 02/057772 A1 discloses an indicator desiccant comprising a silica-based material impregnated with a copper source and a bromide source, where a specific ratio of bromide to copper is taught. WO # 2004/083849 A1 also discloses a comparable indicator desiccant comprising an iron source and a bromide source as an activity indicator system.

However, for these and further indicated desiccants there is a problem with respect to the desiccant capacity remaining after the color change. In particular, there is no reliable means to easily assess when the indicator has to be replaced with a new desiccant in order to maintain the minimum level of drying required after a color change. As a result, although a significant amount of drying force still exists before actually reaching the critical moisture saturation level to further sustain the desired level of drying, the desiccant should generally be replaced immediately after the indicator has changed color.

In this respect, WO # 02/057772 A1 teaches an indicator desiccant comprising copper and bromide as indicators, where the desiccant becomes colorless at somewhat pronounced color transitions at defined levels of saturation by moisture. On the other hand, WO # 2004/083849 A1 teaches the use of iron instead of copper as compared to WO # 02/057772 A1 and shows a second color instead of turning colorless after a somewhat pronounced color transition. Although the second color may develop to some extent in some cases as the saturation of the desiccant with water increases, this may not serve as a reliable indicator of the remaining capacity of the desiccant material. have. In particular, the material shows only a gradual and / or change in color as the humidity increases, so that no practical means can be provided to indicate further saturation of the desiccant by moisture.

Significant problems arise when the indicated desiccant is used in practical applications, where a continuous change occurs in terms of its portion rather than changing the color uniformly. This application is in fact related to tank breathers, etc., where the desiccant is of a certain length that allows the gas to flow freely from the humid environment to the dry environment and / or-if applicable-to the dry environment to the wet environment. Sent to the channel. In this application, the flow rate of the gas can be adjusted to the drying action of the desiccant, thereby forming a color barrier in terms of the color of the indicator in the individual parts of the indicator desiccant. More specifically, this may occur if the part of the desiccant into which the wet gas enters has the color of the saturated desiccant and if the part of the desiccant from which the dried air escapes (and eventually enters) has the color of the dry desiccant. have. Over time, the color barrier in the indicator desiccant suitably wanders from the side where the wet gas enters to the side where the wet gas leaves the material.

For this particular application, the color barrier is an additional indicator because the rate at which the color barrier passes through the desiccant takes into account an estimate of the time remaining before the color barrier passes completely through such material, and accordingly replaced by a new desiccant. Should be. Although this has the advantage that it is possible to approximate the remaining capacity of the desiccant, there is still a general problem that the remaining dry capacity of the material cannot be evaluated after the overall change in color. In addition, the rate at which the barrier crosses the material in this application can only be measured by monitoring the progress over time.

In view of the above, it is an object of the present invention to provide an indicator desiccant in which the indicator reliably reflects the remaining drying capacity of the material after color change.

The above-mentioned object is achieved by the indicator desiccant of the present invention and a method for producing the same. In particular, it has surprisingly been found that it is possible to provide indicator desiccants which exhibit two distinct distinct color changes at different levels of water saturation of the dry material. Due to this feature, a multistage indicating desiccant is provided that allows for improved utilization of the drying properties of the material. In particular, after a first change of color indicating a first degree of saturation by moisture in the dry material, the user-depending on the type of field in which the dry material is used-replaces the desiccant with a new material to ensure the required level of drying. Assess the actual need to Thus, the utilized capacity of the dry material can be optimized in this way.

Therefore,

a) at least one aluminosilica co-gel,

b) one or more sources of iron, and

c) one or more bromide sources

A multistage indicator desiccant comprising: at least one iron source and at least one bromide source are supported at least in part on an aluminosilica co-gel, preferably by impregnation on such a co-gel. will be.

In particular, the surprising use of the aluminosilica co-gel in combination with iron and bromide as active ingredients in the indicator is a distinct color in which the multistage indicator desiccant is distinguished at different levels of saturation of the desiccant component by moisture, in particular by atmospheric moisture. It was found to be able to indicate metastasis.

For the purposes of the present invention, "aluminosilica co-gel" refers to any silica gel into which an appropriate amount of AlO ₂ ^- ions are introduced, generally isomorphous with SiO ₂ . The introduction of aluminum can be achieved by any possible method, wherein the method of co-gelling and / or ion exchange is preferred, in particular for further control of the aluminum content, following co-gelling, Preferably, it is desirable to perform one or more ion exchange steps with a suitable aluminum source to further increase the aluminum content.

In general, the aluminum content of the aluminosilica co-gel used in the multistage indicator desiccant can be adjusted to any possible value provided that the multistage indicator effect defined in the present invention can be provided. For example, the aluminum content is such that the aluminosilica co-gel is 0.1 to 10% by weight of Al, preferably 0.5 to 5% by weight of Al, more preferably 1 to 1, based on the weight of the aluminosilica co-gel. It may be adjusted to contain 2% by weight, more preferably 1.2 to 1.8% by weight, more preferably 1.4 to 1.6% by weight, even more preferably 1.45 to 1.55% by weight of Al.

Co-gelling in the sense of the present invention may involve any process in which alumina gel and silica gel are co-formed and combined to form an aluminosilica co-gel, wherein the gels preferably gel and / or coagulate It is formulated during the coagulation process. In the present invention, it is preferred that the aluminosilica co-gel is at least partially obtained by the process disclosed in DE 29 17 313 A1, wherein the aluminosilica material obtained is at least one with a suitable aluminum source and / or an aluminate ion source. It is more desirable to undergo further ion exchange steps.

Instead of or in addition to this co-gelation process, in the sense of the present invention, aluminosilica co-gels may also be used by ion exchange of aluminum sources with silica-based materials, in particular for ion exchange of silica gels and / or aluminosilica gels. Can be obtained by

The at least one aluminosilicate co-gel used in the present invention is a porous material, and aluminosilica co-gels having any possible porosity can be used provided they exhibit at least partially adequate drying activity. In general, the porosity of the material may range from 0.2 to 0.9 ml / g as measured by N ₂ -Physiosorption according to DIN 66131. Preferably, the porosity of the aluminosilica co-gel is included in the range of 0.3 to 0.7 ml / g, more preferably 0.35 to 0.55 ml / g, even more preferably 0.4 to 0.48 ml / g.

In addition, the BET surface area (according to DIN 66131) of the aluminosilica co-gels used in the present invention may range from 200 to 800 m 2 / g, where preferably the surface area is from 300 to 775 m 2 / g, more preferably. Preferably from 450 to 750 m 2 / g, more preferably from 550 to 725 m 2 / g, even more preferably from 600 to 700 m 2 / g.

In the present invention, the aluminosilica co-gel used may be provided in any macroscopic form if it can act as a multistage indicator desiccant. Thus, for example, the co-gel can be used in powder form, in granulated form, as pellet or as beads, or in a mixture of two or more of the above. Preferably, the aluminosilica co-gel is provided and used in the form of beads. In addition, the aluminosilica co-gel material used in the present invention may preferably be used in the form of a glassy silica gel-like material which is preferably at least partially translucent, and the use of glassy silica gel-like material is preferred, more Preferably the material is substantially translucent.

According to a particularly preferred embodiment of the invention, the aluminosilica co-gels used comprise KC-Trockenperlen® (also known as Sorbead®), even more preferably KC-Trockenperlen®N (also known as Thorbead®R). .

The present invention therefore also relates to a multistage indicating desiccant wherein at least one aluminosilica co-gel is at least partially present in the form of beads or granules, preferably as beads.

According to a preferred embodiment of the invention, the aluminosilica co-gels used are very transparent and / or colorless. This can be achieved, for example, by pretreating the material by any possible means of this purpose, preferably by treatment with an oxidizing agent. As the oxidizing agent, any possible oxidizing agent can be used as long as it can provide a transparent and / or colorless aluminosilica co-gel. Examples of typical oxidants that can be used are chlorine, hypochlorite, chlorite, chlorate, perchlorate, chlorine dioxide, and similar oxidative halogen compounds of fluorine, bromine or iodine, nitric acid, nitrous oxide, ozone, hydrogen peroxide, and examples For example compounds that can generate hydrogen peroxide upon contact with water (including peroxide compounds such as sodium perborate and persulfate), and mixtures of two or more of the aforementioned compounds. The oxidant can be used on its own or, if necessary, in a solution with a suitable solvent, preferably water, more preferably distilled water. Preferably, the oxidant and / or its reducing product is substantially colorless and even more preferably, the oxidant and / or its reducing product is in gaseous form, where the gas may be dissolved in a suitable solvent. Preferably, ozone, hydrogen peroxide, and / or chlorine dioxide are used as oxidants in the present invention, more preferably ozone and / or hydrogen peroxide. When hydrogen peroxide is used as the oxidizing agent, it is preferably used with a suitable solvent, preferably water, even more preferably distilled water.

According to a particularly preferred embodiment of the invention, the aluminosilica co-gel is pretreated with ozone, followed by a step of saturating the ozonated material with water, preferably distilled water, followed by Further treatment with H ₂ O ₂ is more preferred.

Instead of or in addition to pretreatment with oxidants, very transparent and / or colorless aluminosilica co-gels may also be provided by calcination, wherein calcination is preferably from 0.5 to at a temperature in the range from 450 to 600 ° C. 8 hours, preferably 1.0 to 7 hours, more preferably 1.5 to 5 hours, more preferably 2.0 to 4 hours, even more preferably 2.5 to 3.5 hours.

According to a particularly preferred embodiment of the present invention, the calcining of the aluminosilica co-gel is carried out in a calcined moving bed calciner, wherein the calciner preferably has a temperature range in the range of 200 to 500 ° C. The co-gel preferably has a residence time here of 5 to 30 hours, more preferably 10 to 20 hours.

For one or more iron sources included in the multistage indicating desiccant, any possible iron source can be used provided the multistage indicating effects defined in the present invention can be achieved. In general, any suitable iron-containing compound may be used for this purpose, wherein iron is preferably present as Fe (II) and / or Fe (III), more preferably as Fe (III).

For one or more bromide sources included in the multistage indicating desiccant, any possible bromide source can be used if the multistage indicating effect according to the invention can be achieved. In this regard, the selection of one or more bromide sources in connection with providing such an effect may depend on the one or more iron sources used, and conversely, the selection of one or more iron sources may depend on the one or more bromide sources used. It should be noted that

In general, the multistage indicating desiccant may contain any possible amount of iron if a multistage indicating effect is achieved. For example, one or more iron sources may be present in the iron source for the total weight of the indicator desiccant in the indicator desiccant, preferably for the total weight of components a), b), and c) included in the indicator desiccant. It may be present in an amount ranging from 0.05 to 0.2% by weight, preferably the amount of one or more iron sources is 0.06 to 0.16% by weight, more preferably 0.07 to 0.14% by weight, more preferably 0.08 to 0.12% by weight More preferably 0.09 to 0.11% by weight.

With regard to iron, the desiccant of the present invention may contain any possible amount of bromide if a multi-stage indication effect is achieved. For example, the one or more bromide sources are based on Br present in the bromide source relative to the total weight of the indicator desiccant, preferably to the total weight of components a), b), and c) included in the indicator desiccant. It may be present in an amount ranging from 0.1 to 0.5% by weight, preferably the amount of one or more bromide sources ranges from 0.2 to 0.45% by weight, more preferably 0.25 to 0.40% by weight, even more preferably 0.30 to 0.38% by weight. .

In addition, with respect to the amounts of one or more iron sources and bromide sources, each of these amounts is selected such that a multi-step directed effect can be achieved. In this regard, the amount of one or more iron sources is selected in consideration of the amount of one or more bromide sources present in the indicator desiccant, whereas the amount of one or more bromide sources is selected in view of the amount of one or more iron sources present in the indicator desiccant. do. According to a particularly preferred embodiment of the invention, the multistage indicator desiccant is present in the total weight of the indicator desiccant, preferably with respect to the total weight of components a), b) and c) included in the indicator desiccant. At least one iron source in an amount ranging from 0.05 to 0.2 wt% based on each amount of Fe and Br and at least one bromide source in an amount ranging from 0.1 to 0.5 wt%, more preferably from 0.07 to 0.14 Wt% Fe and 0.2 to 0.45 wt% Br, more preferably 0.08 to 0.12 wt% Fe and 0.25 to 0.40 wt% Br, even more preferably 0.09 to 0.11 wt% Fe and 0.30 to 0.38 wt It contains% Br.

Thus, according to one preferred embodiment of the invention, the amount of at least one iron source and at least one bromide source included in the multistage indicating desiccant also has a molar ratio of Fe: Br in the range of 0.2-0.8: 1, preferably 0.3-0.6 : 1, more preferably 0.33-0.55: 1, more preferably 0.35-0.5: 1, even more preferably 0.37-0.45: 1 is selected.

In the sense of the present invention, the feature that at least one iron source and at least one bromide source is at least partially supported on at least one aluminosilica co-gel is such that the components containing Fe and / or Br and / or comprising alumino Absorbed onto at least a portion of the surface of the silica co-gel, preferably these components are evenly distributed over the entire surface of the aluminosilica co-gel. “Surface” of the aluminosilica co-gel preferably means, or even more preferably, the entire surface area of the aluminosilica co-gel accessible by one or more iron sources and / or one or more bromide sources. By the entire surface area of the aluminosilica co-gel contained in and / or contained by each source is accessible.

According to a more preferred embodiment of the invention, the multistage indicator desiccant is present in the total weight of the indicator desiccant, preferably with respect to the total weight of components a), b), and c) included in the indicator desiccant. At least one iron source in an amount ranging from 0.05 to 0.2 weight percent and at least one bromide source in an amount ranging from 0.1 to 0.5 weight percent based on each amount of Fe and Br, wherein the at least one alumino The silica co-gel contains 0.1 to 10% by weight of Al, based on the weight of the aluminosilica co-gel. In this respect 0.07 to 0.14 wt% Fe, 0.2 to 0.45 wt% Br, and 0.5 to 5 wt% Al, more preferably 0.08 to 0.12 wt% Fe, 0.25 to 0.40 wt% Br, and 1 Even more preferred are embodiments comprising from 2% by weight of Al, even more preferably from 0.09 to 0.11% by weight of Fe, from 0.30 to 0.38% by weight of Br, and from 1.4 to 1.6% by weight of Al. In each of the aforementioned embodiments, the one or more aluminosilica co-gels comprise KC-Trockenperlen® (also known as Thorbead®), even more preferably KC-Trockenperlen®N (also known as Thorbead®R). More preferred.

The multistage indicating desiccant of the present invention is further characterized by exhibiting more than one distinct distinct color transition as the saturation of the desiccant with moisture increases when starting from a substantially complete dry state of the desiccant. In particular, a distinct distinct color transition in the sense of the present invention means that an observer can easily distinguish the state of the multistage indicating desiccant before the color transition from the state after the color transition, wherein the act of distinguishing the states Can be performed without requiring a printed color scale or similar auxiliary means to accurately recognize the transition. For the purposes of the present invention, the terms "evolution", "change" and "transition" to refer to the color of the indicator desiccant, provided that the level of humidity and its change may be correlated with the saturation level of the indicator desiccant by moisture. As a function of reflecting the visible color and / or appearance of the indicator desiccant as a function of the level of saturation by the moisture of the dry material depending on the humidity level surrounding the indicator desiccant. In particular, the level of humidity surrounding the indicated desiccant in the sense of the present invention preferably means the relative humidity (RH) of the surrounding environment. Unless stated otherwise, the aforementioned changes are changes caused by the indicator desiccant with increasing saturation level of the indicator desiccant by moisture. For the purposes of the present invention, the moisture level of saturation of the dry material is characterized by an increase in the humidity level followed by an equilibrium of the material to a new constant level of humidity in the surrounding environment. Correlated with the humidity level, the color of the indicator desiccant is thus also an indicator of equilibrium in terms of adsorption and desorption of moisture in a constant humidity environment, preferably expressed in terms of the relative humidity (RH) of the surrounding environment. It should be noted.

In order for the color transition to be distinct and distinct and thus easily recognizable, the color of the indicator desiccant must show a strong change in a relatively narrow range of saturation levels by moisture in the dry material. In addition, the strong change in color of the indicator desiccant must be followed by a phase in which the color of the obtained material remains relatively constant over a relatively large range of saturation levels by the moisture of the dry material. This additional feature is essential for the differentiation of color transitions, since only after that it is possible to clearly recognize the point at which the color transition is completed.

Thus, an essential feature of the indicator desiccant according to the invention is the presence of more than one distinct distinct color transition as described above.

According to certain embodiments of the present invention, the color shift of the multistage indicating desiccant can be quantified by a CIE-Lab color system using respective L * a * b * values. In this case, it is preferred that the first color transition out of the substantially complete drying state of the desiccant is characterized by a rapid decrease in the positive value for the a * component, with a value for a * after color transition from 2 to -2. Particularly preferred is located in the range of, more preferably 1.5 to-1.5, wherein the value for a * reaches a high level of saturation by moisture of the dry material, for example 80% of the surrounding environment. Particular preference is given to maintaining in each range up to the humidity RH. It is further preferred that the initial value for a * before the first color transition is in the range of 5 to 40, preferably 8 to 30, more preferably 10 to 20.

Within the scope of the present invention, the numerical value labeled "% RH" corresponds to the same value as the% relative humidity. Thus, the 50% RH value is used synonymously with the relative humidity of 50%. In particular, 50% RH does not mean a humidity corresponding to 50% of a given relative humidity.

According to this embodiment the second color transition is more preferably characterized by a rapid decrease in the positive value for the b * component, wherein the value for b * is prior to and after the end of the first color transition It is particularly preferred that there is a phase that remains relatively constant while the saturation by the moisture of the dry material increases until the onset of the two color transition. According to these embodiments, immediately before the second color transition, the value for the b * component is particularly preferably included in the range of 10 to 30, more preferably 15 to 20. In addition, in the phase just before the second color transition, the value for the b * component is preferably up to 10% RH, more preferably up to 15, from the ambient environment up to 5% RH to the onset of the second color transition. Moisture due to increased humidity from the ambient environment of% RH, more preferably at most 20% RH, more preferably at most 25% RH, even more preferably at most 30% RH to the onset of the second color transition. To saturation of the dry material by means of greater than ± 5 during the increase, preferably greater than ± 3, more preferably greater than ± 2, even more preferably greater than ± 1 It is desirable not to change. In this case, the increase in saturation of the dry material is related to the increase in saturation occurring after the end of the first color transition and before the onset of the second color transition, preferably during the phase up to the onset of the second color transition. do.

In the above preferred embodiment, for the second color transition, the rapid decrease in the positive value for the b * component is preferably at least 40% reduction, more preferably of b *, at the initial value of b * immediately before said reduction. At least 50% reduction in initial value, more preferably at least 60% reduction in initial value of b *, even more preferably at least 70% reduction in initial value of b *. In addition, with respect to the rapid reduction in the positive value for the b * component for the preferred embodiment, the reduction is at most 40% RH, more preferably at most 30% RH, more preferably at most 20% RH, More preferably it occurs during the saturation increase by moisture of the dry material due to the increase in humidity from the surrounding environment of up to 10% RH, even more preferably up to 5% RH.

With regard to the first color transition in this preferred embodiment, the rapid decrease in the positive a * value is preferably at most 8% RH, more preferably at most 6% RH, more preferably at most 4% RH, even more. Preferably from the onset of said first color transition during the increase in saturation by moisture of the dry material due to the increase in humidity from the ambient environment up to 3% RH to the onset of the first color transition.

However, the quantification of the color transitions disclosed above is not intended to limit the subject matter of the present invention, but rather is merely an illustration of the number of color transitions provided by the indicated desiccant of the present invention. For purposes of the present invention, the "color change" or "color transition" provided by the desiccant of the present invention is generally the color of the material that can be detected by the human eye as compared to the visible appearance of the color prior to the change. Is defined as an arbitrary change in the visible appearance of the change in color from a substantially completely dry initial state to a high level of saturation by moisture, such as in an environment with up to 80% RH or higher relative humidity level of the atmosphere. Compared to the change in color of the desiccant, the observer can visually confirm that a predetermined level of saturation of the desiccant with moisture has been obtained or exceeded. In this respect, the present invention clearly distinguishes and distinguishes color transitions from the visual perception of the eye relative to the overall change in color of the material, in particular the change in a * and b * values, for example in a CIE-Lab color system. Effectively providing a multistage indicating desiccant, which does not show any noticeable overlap. According to a particularly preferred embodiment of the invention, the color shift is not perceived by the human eye as a simple change in contrast or hue, but rather is perceived by the human eye as the presence or absence of such contrast or hue, where such changes are In particular, it may be determined based on an absolute measurement value, not based on a specific type or relative intensity of light or shade that require a relative value for evaluation, such as in the form of a detailed color scale.

Thus, reference to "change in color", "change in color", "color transition" or any other expression relating to these terms used in the present invention, as defined above, is particularly preferred of the invention referred to herein. Refers to a change in color of the indicated desiccant of the present invention as defined for the embodiment.

In general, the color transition represented by the multistage indicating desiccant of the present invention is preferably used throughout the entire process of progressive saturation by moisture of the dry material in which at least two distinct color transitions are included in the indicating desiccant. If observed during the entire course of gradual saturation by moisture of the aluminosilica co-gel included in the desiccant, it can occur within any possible range of saturation levels of the dry material with moisture.

In this respect, the first change in color can occur in principle at any level of saturation of the desiccant of the present invention with water, provided that one or more additional color transitions occur before complete saturation with water. Thus, for example, the first change in color may occur at a relative humidity of an ambient environment of 80% RH or less, 60% RH or less, 40% RH or less, or 20% RH or less. According to a particularly preferred embodiment, the first change in color of the desiccant of the invention is 14% RH or less, preferably 8% RH or less, more preferably 5% RH or less, even more preferably 3% RH or less. Occurs in the relative humidity of the surrounding environment.

With respect to the second change in color of the desiccant of the present invention, the color transition is principally such that a separate order of color transitions is ensured, assuming that this color transition only occurs at sufficient intervals from the complete first color transition. This may occur at any level of saturation of the desiccant with moisture. Thus, for example, a second color transition according to the invention can occur at the saturation level of the desiccant of the invention by atmospheric moisture of at least 10% RH, at least 20% RH, at least 30% RH, at least 40% RH. According to a particularly preferred embodiment, the second change in color of the desiccant is from 15 to 50% RH, preferably from 20 to 45% RH, more preferably from 25 to 40% RH, even more preferably from 28 to 38% It occurs at the relative humidity of the surrounding environment, covered by the RH range.

According to the invention, the first and second transitions are at least 5%, more preferably at least 10%, more preferably at least 15%, more preferably at least 20%, more preferably at 25 relative humidity levels. It is preferred to be distinguished by the range of relative humidity in view of the saturation level of the desiccant with moisture corresponding to an absolute change of at least%, even more preferably at least 30%. However, according to the invention, it is generally preferred that the division of the first and second color transitions correspond to a change in relative humidity of at least 5%. The invention thus also relates to an embodiment wherein said color transitions are distinguished by a relative humidity range of 5% up to 40%, 50%, 60% or a relative humidity range of 5% up to 70%, for example. For purposes of the present invention, the distinction between color transitions refers to the percent absolute change from the relative humidity measured at the completion of the first color transition to the relative humidity at which the starting point of the second color transition is located. In particular, for a given value, for example for an absolute change in relative humidity given in%, for example a 5% change may mean an increase in relative humidity from 30% RH to 35% RH.

According to a further embodiment of the invention, the desiccant of the invention may exhibit a third or further color transition after the second color transition, where applicable, preferably for the second color transition as defined in the present application. The same applies to the third and further color transitions. In particular, with respect to the distinction of the third or further color transition from the immediately preceding color transition, if the third or additional color transition is also applicable, preferably the second color transition for the first color transition is the same to them. Is applied.

According to a preferred embodiment of the present invention, it leads to a state of indicator desiccant which can be considered colorless according to the visual perception due to the second or further color transition, where this colorless state is the second color transition of the indicator desiccant of the present invention. Particular preference is given to achieving at the end of. In particular, for the purposes of the present invention, "colorless" refers to a state in which the visible appearance of the multistage indicating desiccant is very similar to that of the aluminosilica co-gel without the indicating compound, and in particular, the visible appearance of the multistage indicating desiccant is one. It refers to a state similar to the appearance of an aluminosilica co-gel without the above iron sources and / or one or more bromide sources. In view of the CIE-Lab color system, the colorless state preferably has a * value of the indicated desiccant of the present invention of ± 5, more preferably ± 3, more preferably ± 2, even more preferably ± 1.5 It refers to a state that does not exceed. In particular, however, the colorless state is such that the a * value exceeds ± 5 from the reference value, preferably ±, as compared to the a * value obtained for the aluminosilica co-gel without the indicating compound as defined above. More than 3, more preferably more than ± 2, even more preferably more than ± 1.5. In the case of the b * value, the colorless state is preferably a state in which the value does not exceed ± 10 for the indicated desiccant of the invention, more preferably does not exceed ± 8, more preferably greater than ± 6 More preferably, not more than ± 4, more preferably not more than ± 3, even more preferably not more than ± 2. For a * values, the colorless state is preferably such that the b * value exceeds ± 5 from the reference value when compared to the b * value obtained for the aluminosilica co-gel without the indicating compound as defined above. , Preferably more than ± 3, more preferably more than ± 2, even more preferably more than ± 1.5.

For the purposes of the present invention, with respect to the state of the colorless indicator desiccant, the indicator desiccant according to the invention is at least 75% RH, preferably at least 60% RH, more preferably at least 50% RH, more preferably 45 Particular preference is given to changing colorless at a relative humidity of at least% RH, even more preferably at least 40% RH.

In principle, the multistage indicating desiccant according to the invention is prepared by any possible method, provided that it exhibits the features of the invention as defined above for embodiments of the invention, in particular for preferred embodiments of the invention. Can be.

The invention further relates to a process for the preparation of a multistage indicating desiccant. In general, the indicator desiccant of the present invention as defined above may be obtained by any suitable method capable of providing an indicator desiccant capable of exhibiting the features of the present invention disclosed above.

According to certain embodiments of the invention, the multistage indicating desiccant

(i) providing at least one aluminosilica co-gel;

(ii) impregnating the aluminosilica co-gel with one or more sources of iron;

(iii) impregnating the aluminosilica co-gel with one or more bromide sources; And

(iv) drying the impregnated aluminosilica co-gel

It is prepared by a method comprising,

Wherein the aluminosilica co-gel impregnated in step (iv) is optionally washed before its drying.

In the production process of the invention, the aluminosilica co-gel provided in step (i) is preferably an aluminosilica co-gel as defined above. In particular, according to a preferred embodiment of the invention, the aluminosilica co-gel provided in step (i) is 0.1 to 10% by weight of Al, preferably 0.5 to 5% by weight, based on the weight of the aluminosilica co-gel. % Al, more preferably 1 to 2% by weight, more preferably 1.2 to 1.8% by weight, more preferably 1.4 to 1.6% by weight, even more preferably 1.45 to 1.55% by weight of Al. According to a particularly preferred embodiment of the present invention, the method of preparation comprises aluminosilica co- comprising KC-Trockenperlen® (also known as Thorbead®), even more preferably KC-Trockenperlen®N (also known as Thorbead®R). Gel is used.

For one or more iron sources that can be used in the production process of the invention, any possible source can be used if it contains one or more Fe (II) and / or Fe (III) -sources, where one or more Fe (III) Use of a source is preferred. According to a particularly preferred embodiment of the invention, said source comprises at least one Fe (III) -salt, preferably Fe (III) sulphate, wherein the Fe (III) -salt is more preferably (NH ₄ ) Fe (SO ₄ ) ₂ and / or KFe (SO ₄ ) ₂ , even more preferably (NH ₄ ) Fe (SO ₄ ) ₂ .

For one or more bromide sources that can be used in the production process of the invention, any possible source can be used, wherein the one or more bromide sources are preferably NaBr, KBr, CaBr, MgBr, (NH ₄ ) Br, and these At least one bromide salt selected from the group consisting of two or more mixtures thereof. According to a particularly preferred embodiment, the at least one bromide source comprises NaBr and / or (NH ₄ ) Br, more preferably NaBr.

According to the preparation process of the present invention, the impregnation of the aluminosilica co-gel provided in step (i) is any possible if the indicator desiccant obtained effectively supports both iron and bromide, preferably Fe (III) and bromide. Can be done in a manner. In particular, the impregnation of the aluminosilica co-gel may be carried out by impregnating at least one iron source (ii) followed by impregnating at least one bromide source (iii). However, according to an alternative embodiment of the invention, a step of impregnating the aluminosilica co-gel with one or more bromide sources according to step (iii) followed by impregnation of the co-gel with one or more iron sources The order of the above steps can be reversed so that For the purposes of the present invention, the impregnation steps (ii) and / or (iii) may be repeated equally as many times as necessary to achieve the desired loading of iron and bromide on the aluminosilica co-gel.

However, in the present invention, it is preferred to perform steps (ii) and (iii) at least partially simultaneously, ie in one or more common steps of impregnation, wherein the simultaneous impregnation step may be repeated one or more times. The invention therefore also relates to a process for the preparation of at least partially simultaneously carrying out steps (ii) and (iii) by impregnating the aluminosilica co-gel with at least one iron source and at least one bromide source. However, the present invention also relates to the alumina according to steps (ii) and / or (iii) prior to and / or after said one or more impregnation steps in which steps (ii) and (iii) are carried out simultaneously in one or more common steps. Includes embodiments in which one or more individual steps of impregnating nosilica co-gel can be performed.

In general, the one or more steps of impregnating the aluminosilica co-gel with one or more iron sources and / or one or more bromide sources according to the present invention may be performed as long as appropriately impregnated aluminosilica co-gels are obtained. Can be carried out by means. Thus, with regard to the actual action of impregnating the aluminosilica co-gel as defined in each of steps (ii) and (iii), any possible impregnation method can be used, where impregnation is soaking or initial It is preferably achieved by a process of incipient wetness.

Thus, in the present invention, it is preferred that the impregnation of the aluminosilica co-gel is achieved with one or more suitable solvents. In principle, for this purpose any solvent can be used provided that at least one iron source and / or at least one bromide source can be properly dispersed and / or dissolved for the impregnation step. In particular, the solvents preferably used in the present invention comprise water, and according to particularly preferred embodiments, the solvent consists substantially of water, even more preferably the solvent is distilled water.

According to a preferred embodiment of the invention in which a solvent consisting essentially of water, preferably distilled water, is used, the pH of such aqueous solution containing at least one iron source and / or at least one bromide source is at least one aluminosilica coco. Any suitable pH may be taken as appropriate for the impregnation of the gel. Preferably, the aqueous solution used in the present invention has a pH in the range of 0.5 to 5.0, more preferably pH is 0.8 to 3.0, more preferably 0.9 to 2.0, more preferably 1.0 to 1.6, more preferably Preferably from 1.1 to 1.5, even more preferably from 1.2 to 1.4.

According to an embodiment of the process of the invention, in which the impregnation solution is used in steps (ii) and / or (iii) and / or in which steps (ii) and (iii) are carried out at least partially in one or more common impregnation steps, The amount of the above iron source and / or one or more bromide sources is generally chosen such that the required loading of the aluminosilica co-gel is achieved in order to further obtain the multistage indicating desiccant according to the invention according to the specific impregnation technique. Thus, according to certain embodiments, the amount of one or more bromide sources used is chosen such that the resulting impregnation solution comprises 0.5 to 4 wt% bromide, wherein the obtained impregnation solution is 1-3 wt%, more preferably 1.5 to 2.5 It is preferred to comprise bromide by weight, more preferably 1.7 to 2.2% by weight, more preferably 1.9 to 2.0% by weight and even more preferably 1.92 to 1.96% by weight. In addition, with respect to the amount of one or more iron sources selected for use in the production process of the present invention, the amount is such that the resultant impregnation solution is from 0.02 to 0.2% by weight of iron, preferably from 0.05 to 0.15% by weight, more preferably 0.07 To 0.13% by weight, more preferably 0.08 to 0.11% by weight, more preferably 0.085 to 0.10% by weight, even more preferably 0.090 to 0.096% by weight of iron. According to a particularly preferred embodiment of the process of the invention wherein steps (ii) and (iii) are carried out at least partially simultaneously in one or more common impregnation steps, the amount of both the at least one iron source and the at least one bromide source is obtained. It is preferred that it is selected in the manner specified above for each of the amounts of bromide and iron expressed in weight percents included in.

According to the invention, the preferred impregnation solution, more preferably the amount of iron and / or bromide contained in the aqueous solution, refers to the amount of such element present in the solution, regardless of the state of the element contained in the solution. However, the amount of iron and / or bromide contained in the impregnation solution, each expressed in weight percent, refers to the iron and / or bromide dissolved in the impregnation solution, ie, their amount in the solvated state. .

In the process of the invention, at least one aluminosilica co-gel is suitable for impregnation with at least one impregnation solution comprising at least one iron source and / or at least one bromide source, preferably iron and / or bromide. If so, it may be provided in any possible state, wherein the impregnation solution is preferably an impregnation aqueous solution. In this aspect, the aluminosilica co-gel is prepared prior to the impregnation of steps (ii) and / or (iii), or in steps (ii) and (iii), to enable and / or enhance subsequent impregnation treatment. It is preferred to undergo one or more treatment steps prior to the simultaneous impregnation step. To this end, at least one treatment step in the process of the invention preferably comprises saturating the aluminosilica co-gel with a solvent, and preferred embodiments involving the use of an impregnation solution, preferably an aqueous solution of impregnation. According to the invention, the solvent is the same solvent as used in the impregnation solution which is used later for the impregnation step with at least one iron source and / or at least one bromide source. Thus, according to a particularly preferred embodiment of the invention using an aqueous solution for impregnation with iron and / or bromide, the aluminosilica co-gel is preferably alumino in water, preferably by saturation with water, preferably in water Pretreated by immersing the silica co-gel, even more preferably the water used for this purpose is distilled water.

Thus, the process of the invention also relates to a preferred embodiment in which the aluminosilica co-gel is saturated with water, preferably immersed in water, prior to steps (ii) and / or (iii). The water used as is preferably distilled water.

In general, the impregnation of steps (ii) and / or (iii), and the simultaneous impregnation step as defined above, comprise at least one iron source and / or at least one bromide source used in each step, each used amount, And the impregnation time is selected so that the desired loading of the aluminosilica co-gel for this step is achieved according to the impregnation method used. According to a preferred embodiment of the invention where the impregnation is carried out by dipping and / or initial wetting using an impregnation solution, the impregnation is preferably from 0.5 to 24 hours, more preferably from 1 to 16 hours, more preferably 4 to 12 hours, more preferably 6 to 10 hours, even more preferably 7 to 9 hours.

Furthermore, with regard to the drying of the impregnated product according to step (iv) of the production process of the invention, the drying can be carried out at any suitable temperature for any possible time, wherein preferably the drying conditions are produced It is chosen so that a substantially dry product is obtained in view of the material being substantially free of adsorbed water and thus actually having a maximum moisture adsorption capacity. According to certain embodiments of the invention, the drying of step (iv) is 80 to 220 ° C., preferably 100 to 190 ° C., more preferably 120 to 170 ° C., more preferably 130 to 160 ° C., even more preferred. Preferably at a temperature comprised in the range from 140 to 150 ° C. Furthermore, there is no limitation on the duration of the drying step if the desired level of drying can be achieved in the indicated desiccant, but the drying is preferably 0.2 to 8 hours, more preferably 0.5 to 4 hours, even more preferably It is carried out for a time in the range of 1 to 2 hours.

In the process of the invention, the drying step according to step (iv) is carried out at least once after impregnating the aluminosilica co-gel with iron and bromide in at least one step, with or without pre-washing. According to an embodiment of the present invention in which the order of steps (ii) and (iii) may be alternating as described above, step (iv) is performed appropriately after step (ii) (preceded by step (iii)). Can be. Furthermore, according to a preferred embodiment involving one or more steps of simultaneous impregnation with both iron and bromide as defined above, step (iv) is then carried out as appropriate.

According to a further embodiment of the production process of the present invention, the one or more additional drying steps may be carried out between or between steps (ii) and (iii), depending on the order of selection of the impregnation step, with or without optional pre-washing. It can be carried out between iii) and (ii). Furthermore, in addition to one or more steps of co-impregnation with iron and bromide, it involves one or more individual steps of impregnation according to steps (ii) and / or (iii) performed before and / or after one or more steps of co-impregnation. In connection with an embodiment, one or more additional drying steps may be performed between any two successive impregnation steps, with or without optional pre-washing.

In addition to the multistage indicating desiccant as defined above, the present invention also relates to a multistage indicating desiccant which can be obtained, ie obtainable according to the process of the invention for the preparation of the multistage indicating desiccant as defined in the present application.

The invention thus also relates to a multistage indicating desiccant which can be obtained according to the process of the invention.

In addition to the multistage indicating desiccant and the process for preparing the multistage indicating desiccant as defined above, the invention also relates to the use of the multistage indicating desiccant. In general, the multi-step indicator desiccant defined in the present application can be used in any possible manner, the use of which as desiccant and / or moisture indicator is preferred.

The invention therefore also relates to the use of a multistage indicating desiccant as defined above for desiccant and / or for moisture monitoring.

For the purposes of the present invention, moisture refers to any type of content with water in a material selected from the group of solid, liquid and gaseous materials or a combination of one or more materials. Preferably, for the purposes of the present invention, moisture refers to the water content of liquids and / or gases, more preferably gases, and particularly preferably, moisture can be expressed in terms of relative humidity. Refers to moisture.

According to certain embodiments of the invention, the multistage indicating desiccant is in a gas drying column, in a transformer breather, in a tank breather, in a protective device for electronics, in particular for a telecommunications system, and / or in a laboratory dryer. Used. Also and in particular, multistage indicating desiccants can be used in the fields involving the packaging of the material, in particular in the packaging of health care and / or pharmaceutical products. In the field involving the packaging of the material, multistage indicating desiccants are preferably used in the container lids or stoppers in which the dry material is contained and / or in the container.

Example

Example  One

KC-Trockenperlen®N (BASF) is pretreated by calcination in a direct-fired (natural gas) moving bed calciner with a temperature zone in the range of 200-500 ° C. and an average residence time of 15 hours.

After cooling, 400 g of the pretreated aluminosilica co-gel are slowly saturated with 300 ml water. The water is then poured off and the support material is immersed in 235 ml of impregnation solution containing 25 g / L NaBr and 8 g / L (NH ₄ ) Fe (SO ₄ ) ₂ * 12 H ₂ O. After 4 hours of immersion, the solution is poured off and removed, and the resulting aluminosilica co-gel is washed with 300 ml of water and then dried at 145 ° C. for 12 hours. The dried product is dark red.

element:

Al 1.5 wt%

Fe 0.1 wt%

Br 0.3 wt%

Starting from the dry material (Sample A), a sample was prepared with a degree of saturation defined by atmospheric moisture. More specifically, Samples B, C, D, and E were prepared at defined humidity of 10% RH, 20% RH, 40% RH, and 80% RH, respectively. The specified humidity reflects the state of the indicator desiccant when the sample desiccant sample is held in air of a predetermined humidity for a time sufficient to achieve equilibrium therein in terms of moisture exchange with this atmosphere. During the equilibrium phase of the sample, the relative humidity of the air surrounding the sample is maintained at a value determined by appropriate humidification means. Alternatively, an air stream of defined relative humidity may pass through the sample until the sample reaches equilibrium. Sample A of ˜0% relative humidity corresponds to the sample obtained directly in Example 1 after the drying step, where the sample is cooled in an atmosphere of ˜0% relative humidity.

Color test

The color of the sample obtained in Example 1 was measured using a PerkinElmer Lambda 900 spectrometer (150 mm integrating sphere) using CIE Illuminant C and an observation angle of 2 ° and calibrated with Standard White (Spectralon® Reflectance Standard). L * a * b * system (L * represents brightness (higher values, brighter), a * represents red / green components (positive values are red, negative values are green), b * Indicates the yellow / blue component (positive values are yellow and negative values are blue).

Sample RH  [%] L * a * b * color A ~ 0 52.1 14.4 26.0 Dark red B 10 60.0 -0.3 17.4 yellow C 20 59.9 0.9 18.1 yellow D 40 66.6 -1.2 7.8 Colorless E 80 69.8 -1.0 1.9 Colorless

For comparison, commercially available indicator desiccant SORBSIL® CHAMELEON® (Oker-Chemie GmbH) (hereinafter referred to as "SC"), and KC-Trockenperlen® Orange CHAMELEON ^™ (BASF) (hereinafter referred to as "TP-OC") Appropriately tested).

Sample RH  [%] L * a * b * color SC dry ~ 0 60.4 7.6 33.6 amber SC 10 10 60.6 7.8 32.1 amber SC 20 20 64.0 6.5 32.1 amber SC 40 40 71.5 -1.6 24.6 Light amber SC 80 80 74.8 -3.3 18.6 Light amber

Sample RH  [%] L * a * b * color TP-OC drying ~ 0 53.2 3.2 26.7 orange color TP-OC 80 80 69.7 -0.8 1.2 Colorless

discussion

As shown in the results of Table 1 for Samples A-E obtained in Example 1, the indicator desiccant according to the present invention shows two distinct and distinct color transitions at various saturation levels of the desiccant with atmospheric moisture. In particular, as can be seen from the change in the a * value with increasing saturation level, the first color transition occurs between the dry state of sample A and the saturation level of desiccant in air with 10% relative humidity shown in sample B. . This color shift is perceived by the human eye as yellow in a sample prepared at 10% relative humidity in dark red in a dry sample.

With regard to the color values, it should be noted that the a * component is clearly superior in the visual detection of color changes such that the initial intensity of the b * component and its variation during the first color transition are neglected. SORBSIL® color transition to CHAMELEON® and sample B in a KC-Trockenperlen® Orange CHAMELEON ^TM sample A in compared to the results of the Table 2 and 3 using each of Table 1, as well as more pronounced in fact the human eye It is clear that this leads to a * values involving color transitions that cannot be detected. In addition, in terms of visual sensing of the color components, the a * value remains negligible up to the high saturation level of the indicated desiccant by moisture, as can be seen from the results for sample CE in Table 1. This feature of the indicated desiccant of the present invention is the most important of the surprising features of the present invention, because any significant rest- or resurging component of the predominant a * component is due to a change in the b * component. This is because it cannot block human visual perception of additional color transitions.

Thus, as can be seen from the change in the b * values shown in Table 1 for Samples C and D of Example 1, the second color transition from bright amber in Sample C to actually colorless in Sample D was observed in the human eye. This is very well recognized because the a * value is present enough to completely ignore the sample BE. Further, the first color transition reflecting a marked change in the a * value from sample A to B followed by the addition of saturation for samples B and C of Example 1 prepared at relative humidity of 10% RH and 20% RH respectively. In terms of increase, followed by a plateau region with respect to the change in b * value with increasing humidity levels, as shown in Samples B and C. This represents a combination effect of the following, one clearly defining the first color transition (because immediately following the transition followed by a constant color phase for further increase in relative humidity for the first part), and the other One clearly defines the second color transition that occurs between the relative humidity of 20% RH and 40% RH as shown for samples C and D of Example 1 (when reaching the saturation range by atmospheric moisture). Until the color of the desiccant does not change further). Thus, in the desiccant of the present invention the "static" region with respect to the color change is an additional feature that enables the surprising technical effect of the present invention. This also applies to the additional "static" region following the second color transition that occurs between a relative humidity of 20% RH and 40% RH, the sample obtained is illustrated by the results for Samples D and E of Example 1 shown in Table 1 As can be seen, the human eye remains colorless through the further saturation of the desiccant of the present invention with moisture as the relative humidity of the surrounding atmosphere increases.

Thus, as can be seen from the results for the color test performed on the sample obtained in Example 1 when compared to the exemplary indicator desiccant of the prior art, the intrinsic coordinates of the a * and b * values achieved by the present invention are It delivers some of the industry's most distinctive and technical advantages. More specifically, this surprising color behavior of the indicator desiccant according to the invention enables a series of distinct and distinct color transitions which are characteristic of the multistage indicator desiccant provided herein.

Claims (22)

a) at least one aluminosilica co-gel,
b) one or more sources of iron, and
c) one or more bromide sources
As a multiple-stage indicating desiccant, the at least one iron source and at least one bromide source are at least partially supported by impregnation on an aluminosilica co-gel, preferably on such a co-gel. Multistage indicating desiccant. The multistage indicating desiccant according to claim 1, wherein the at least one aluminosilica co-gel is at least partially present in the form of beads or granules, preferably as beads. The method of claim 1 or 2, wherein at least one iron source is added to the iron source relative to the total weight of the indicator desiccant, preferably to the total weight of components a), b), and c) included in the indicator desiccant. It is present in an amount ranging from 0.05 to 0.2% by weight based on Fe present, preferably the amount of one or more iron sources is 0.06 to 0.16% by weight, more preferably 0.07 to 0.14% by weight, more preferably 0.08 to 0.12 Multistage indicating desiccant in the range by weight, even more preferably 0.09 to 0.11% by weight. The method of claim 1, wherein the one or more bromide sources are based on the total weight of the indicator desiccant, preferably on the total weight of components a), b), and c) included in the indicator desiccant. It is present in an amount ranging from 0.1 to 0.5% by weight, based on Br present in the bromide source, preferably the amount of one or more bromide sources is 0.2 to 0.45% by weight, more preferably 0.25 to 0.40% by weight, even more preferred. Multistage indicating desiccant, preferably in the range of 0.30 to 0.38% by weight. The aluminosilica co-gel of claim 1, wherein the aluminosilica co-gel is 0.1 to 10% by weight of Al, preferably 0.5 to 5% by weight of Al, based on the weight of the aluminosilica co-gel. More preferably 1 to 2 wt% Al, more preferably 1.2 to 1.8 wt% Al, more preferably 1.4 to 1.6 wt% Al, even more preferably 1.45 to 1.55 wt% Al A multistage indicating desiccant, containing. The method according to any one of claims 1 to 5, wherein the Fe: Br molar ratio is in the range of 0.2-0.8: 1, preferably in the range of 0.3-0.6: 1, more preferably in the range of 0.33-0.55: 1, More preferably, it is contained in the range of 0.35-0.5: 1, More preferably, it is contained in the range of 0.37-0.45: 1. The method according to any one of claims 1 to 6, wherein the first change in color of the desiccant is 14% RH or less, preferably 8% RH or less, more preferably 5% RH or less, even more preferably A multistage indicating desiccant that occurs at relative humidity below 3% RH. 8. The method of claim 1, wherein the second change in color of the desiccant is between 15 and 50% RH, preferably between 20 and 45% RH, more preferably between 25 and 40% RH. Multi-level indicator desiccant preferably occurs at relative humidity in the range of 28 to 38% RH. The desiccant according to any one of the preceding claims, wherein the desiccant is at least 95% RH, preferably at least 90% RH, more preferably at least 70% RH, more preferably 50% starting from the relative dry state. A multistage indicating desiccant which turns colorless at a relative humidity of at least RH, more preferably at least 45% RH, even more preferably at least 40% RH. (i) providing at least one aluminosilica co-gel;
(ii) impregnating the aluminosilica co-gel with one or more sources of iron;
(iii) impregnating the aluminosilica co-gel with one or more bromide sources; And
(iv) drying the impregnated aluminosilica co-gel
As a method for producing a multi-stage indicating desiccant,
The aluminosilica co-gel impregnated in step (iv) is optionally washed prior to its drying,
Preferably steps (ii) and (iii) are performed at least partially simultaneously by impregnating the aluminosilica co-gel with both one or more iron sources and one or more bromide sources. The aluminosilica co-gel provided in step (i) is 0.1 to 10% by weight of Al, preferably 0.5 to 5% by weight of Al, based on the weight of the aluminosilica co-gel. Preferably 1 to 2% by weight of Al, more preferably 1.2 to 1.8% by weight of Al, more preferably 1.4 to 1.6% by weight of Al, even more preferably 1.45 to 1.55% by weight of Al How. 12. The method according to claim 10 or 11, wherein the at least one iron source comprises a Fe (II) and / or Fe (III) -source, preferably a Fe (III) -source, wherein the Fe (III) -source is Preferably Fe (III) -salts, more preferably (NH ₄ ) Fe (SO ₄ ) ₂ and / or KFe (SO ₄ ) ₂ , even more preferably (NH ₄ ) Fe (SO ₄ ) ₂ Which method. The bromine salt of claim 10, wherein the at least one bromide source comprises a bromide salt selected from the group consisting of NaBr, KBr, CaBr, MgBr, (NH ₄ ) Br, and mixtures of two or more thereof, The at least one bromide source preferably comprises NaBr and / or (NH ₄ ) Br, more preferably NaBr. 14. The process according to any one of claims 10 to 13, wherein steps (ii) and (iii) comprise an aluminosilica co-gel preferably in immersion with an impregnation solution comprising at least one iron source and at least one bromide source. And / or by impregnation by an initial wetting technique. The impregnation solution of claim 14 preferably has a pH in the range from 0.5 to 5.0, preferably in the range from 0.8 to 3.0, more preferably in the range from 0.9 to 2.0, more preferably in the range from 1.0 to 1.6, more preferably 1.1. To 1.5, more preferably 1.2 to 1.4. The impregnating solution according to claim 14 or 15, wherein the impregnation solution is from 0.5 to 4% by weight of bromide, preferably from 1 to 3% by weight of bromide, more preferably from 1.5 to 2.5% by weight of bromide, more preferably from 1.7 to 17%. 2.2 wt% bromide, more preferably 1.9 to 2.0 wt% bromide, even more preferably 1.92 to 1.96 wt% bromide, and the impregnation solution is 0.02 to 0.2 wt% iron, preferably 0.05 to 0.15 wt% iron, more preferably 0.07 to 0.13 wt% iron, more preferably 0.08 to 0.11 wt% iron, more preferably 0.085 to 0.10 wt% iron, even more preferably 0.090 to 0.096 Further comprising wt% iron. The water according to any one of claims 10 to 16, wherein prior to step (ii) and / or (iii) the aluminosilica co-gel is preferably saturated with water by immersion in water and used for this purpose. Is preferably distilled water. 18. The process of any of claims 10 to 17, wherein the impregnation of steps (ii) and / or (iii) is by dipping and / or by initial wetting, preferably from 0.5 to 24 hours, more preferably The process is carried out for a period ranging from 1 to 16 hours, more preferably 4 to 12 hours, more preferably 6 to 10 hours, even more preferably 7 to 9 hours. 19. The process of any of claims 10-18, wherein the drying of step (iv) is from 80 to 220 ° C, preferably from 100 to 190 ° C, more preferably from 120 to 170 ° C, more preferably from 130 to 160. C, even more preferably at a temperature comprised in the range from 140 to 150 ° C., the drying is preferably in the range from 0.2 to 8 hours, more preferably from 0.5 to 4 hours, even more preferably from 1 to 2 hours. Which is carried out for a time. A multistage indicating desiccant obtainable according to the method of any one of claims 10-19. Use of a multistage indicating desiccant according to any one of claims 1 to 9 and 20 as a desiccant and / or for moisture monitoring. The method of claim 21, wherein the multistage indicating desiccant is in a gas drying column, in a transformer breather, in a tank breather, in a protective device for electronics, in particular for a telecommunications system, in a laboratory dryer, and / or of material. In the field involving packaging, in particular in the packaging of health care and / or pharmaceutical products, the multi-level indicator desiccant is preferably used in a container lid or cap and / or in a container comprising a dry material.